SAN for beginners

SAN for beginners

[Beginner]

Hi All,

I need to add some about 10TB of storage to our infrasturce and went 
along to an storage exhibition to find out what was available. The 
biggest grey area for me was the filesystem and management. Without 
being too open-ended, I want to get some idea of what Linux-based 
solution I could use. All the manufacturers I talked to had no idea 
about how to manage and share their products unless they were Windows 
based even though they claim to support Linux.

I had been presuming I would install the SAN gateway and the storage 
arrays, use LVM for the filesystem and Samba to share the data to 
Windows user and install Fibre-Channel cards to the other 3 servers 
that need access to the data. However I think that there is more to 
it than that and I could use some help understanding how it all hangs 
together and what (Linux) options there are. If there servers are to 
see the storage as block devices I imagine there is some proprierty 
software needed for the OS's. 

Currently I use FC4 on my servers and the are about 40 Windows users 
that need to access the data as well.

Any thoughts or advice is much appreciated.
Thanx,
Dp.

Re: SAN for beginners

[ycsapo]

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Hi Dermot,

As I'm sure you know, volumes could be (and have been) written about the
subject. Where I work we have a few different SAN type solutions and
without going into any details, this is a brief list of topics you may
want to get up to speed on:

- - Fiber channel vs. iSCSI
- - QLogic products for fiber channel
- - GFS - the global file system by RedHat

Very briefly, one of the systems I manage is a Hitachi SAN built around
a McData switch that has 2 fiber channel and 2 fiber gig-e ports; the
disks are all fiber channel but the servers connect to the SAN via the
fiber ethernet using iSCSI.

- From then on, LUNs on the SAN are seen by the servers as block devices
and. If you have separate LUNs for each server, you can just do what you
said: LVM -> samba. If you plan to have more than one server mounting
the same LUN (for redundancy perhaps) you need something like GFS which
will handle consistency and locking across the servers.

HTH

Beginner wrote:
> Hi All,
> 
> I need to add some about 10TB of storage to our infrasturce and went 
> along to an storage exhibition to find out what was available. The 
> biggest grey area for me was the filesystem and management. Without 
> being too open-ended, I want to get some idea of what Linux-based 
> solution I could use. All the manufacturers I talked to had no idea 
> about how to manage and share their products unless they were Windows 
> based even though they claim to support Linux.
> 
> I had been presuming I would install the SAN gateway and the storage 
> arrays, use LVM for the filesystem and Samba to share the data to 
> Windows user and install Fibre-Channel cards to the other 3 servers 
> that need access to the data. However I think that there is more to 
> it than that and I could use some help understanding how it all hangs 
> together and what (Linux) options there are. If there servers are to 
> see the storage as block devices I imagine there is some proprierty 
> software needed for the OS's. 
> 
> Currently I use FC4 on my servers and the are about 40 Windows users 
> that need to access the data as well.
> 
> Any thoughts or advice is much appreciated.
> Thanx,
> Dp.
> 
> 
> 
> -
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- --
Yuri Csapo
Academic Computing & Networking
Colorado School of Mines
Green Center Rm 249
Phone:  (303) 273-3503
Fax:      (303) 273-3475
Email:   ycsapo@mines.edu

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===========================================
With a PC, I always felt limited
by the software available.
On Unix, I am limited only by my knowledge.
- --Peter J. Schoenster
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Re: SAN for beginners

[urgrue]

> I need to add some about 10TB of storage to our infrasturce and went 
> along to an storage exhibition to find out what was available. The 
> biggest grey area for me was the filesystem and management.

For starters, are you sure you need SAN? SAN is great and wonderful, but
it is quite expensive, and I know from experience that the salesmen at
storage exhibitions will happily try and sell you on SAN even if
alternative (cheaper) solutions (such as NAS or iSCSI) would suffice.

> I had been presuming I would install the SAN gateway and the storage 
> arrays, use LVM for the filesystem and Samba to share the data to 
> Windows user and install Fibre-Channel cards to the other 3 servers 
> that need access to the data.

As someone already pointed out, the 3 servers wont see the same data as
the computers mounting it via samba, not without GFS or something
similar. Same with iSCSI.
If they do need access to the same data, this is the point where one
should asks themselves if NAS might suit you better after all.

> If there servers are to 
> see the storage as block devices I imagine there is some proprierty 
> software needed for the OS's. 

The only proprietary software you need is the driver that comes with the
1000 dollar FC card.
iSCSI can be done using free software over a normal ethernet card but it
eats up a lot of CPU and you wont get very good performance out of it
(but its still pretty good).

Re: SAN for beginners

[Brett Zimmerman]

On Wed, 18 Oct 2006, Beginner wrote:

> Hi All,
>
> I need to add some about 10TB of storage to our infrasturce and went
> along to an storage exhibition to find out what was available. The
> biggest grey area for me was the filesystem and management. Without
> being too open-ended, I want to get some idea of what Linux-based
> solution I could use. All the manufacturers I talked to had no idea
> about how to manage and share their products unless they were Windows
> based even though they claim to support Linux.
>
> I had been presuming I would install the SAN gateway and the storage
> arrays, use LVM for the filesystem and Samba to share the data to
> Windows user and install Fibre-Channel cards to the other 3 servers
> that need access to the data. However I think that there is more to
> it than that and I could use some help understanding how it all hangs
> together and what (Linux) options there are. If there servers are to
> see the storage as block devices I imagine there is some proprierty
> software needed for the OS's.
>
> Currently I use FC4 on my servers and the are about 40 Windows users
> that need to access the data as well.
>
> Any thoughts or advice is much appreciated.
> Thanx,
> Dp.
>

With a FC4 setup, you may want to look at Red Hat Cluster Suite / GFSJ. 
GFS allows for parallel access to filesystems, and the cluster 
suite provides a nice management interface and failover.  A nice plus is 
that it's open source, the code is available from sources.redhat.com, and 
at least the GFS modules are included in recent FC releases.  I'm not 
sure whether there are stock rpms for the cluster management stuff, but 
again, they're not at all difficult to build.

-bz

-- 
Brett Zimmerman
zim@oscer.ou.edu
(405)826-5104